1. Field of the Invention
The invention relates generally to the field of horticulture and more specifically to plant watering systems (“PWS”, see Definitions section).
2. Description of the Related Art
Many PWSs are conventional. PWSs with planters (see Definition of PWS) that include certain types of soil moisture sensors and/or various other features are conventional. Irrigation type PWSs (see Definition of PWS) that include certain types of soil moisture sensors and/or various other features are conventional. Some existing publications relating to PWSs with planters and to irrigation type PWSs will now be discussed.
U.S. Pat. No. 4,001,967 (“Swift”) discloses a self-watering planter including an inner shell, an outer shell and a reservoir tank formed by and located between the two shells. Water is fed from the reservoir to soil and plants within the inner shell by vacuum control and capillary action. Swift also discloses a water level indicating plug built into an exterior surface of its reservoir tank. The plug of Swift is tapered and transparent, and it is constructed so that more ambient light will be reflected toward users if the reservoir water level is below the height of the plug than when the water level is above the height of the plug. This provides the user with a visual indication of the water level in the reservoir of the self-watering planter of Swift.
U.S. Pat. No. 4,241,538 (“Lahr”) discloses a device for automatically watering plant containers including a supply hose threaded through a pair of resilient members. A planter with soil is placed on top of the resilient members. When the soil is relatively wet, the weight of the planter forces the resilient members, against their bias, into a closed position, whereby the resilient members squeeze shut the supply hose and cut off the water supply. When the soil is dry, the bias of the resilient members forces them into an open position, whereby the supply hose is no longer squeezed or pinched shut by the resilient members and water can flow through the supply hose to the dry soil.
U.S. Pat. No. 4,829,709 (“Centafanti”) discloses a planter including an upper receptacle that holds soil and a plant and a lower receptacle which is a reservoir that holds water. Under appropriate soil moisture conditions in the upper receptacle, a wick member draws water up from the lower receptacle into the upper receptacle to water the plant.
U.S. Pat. No. 4,834,265 (“Snyder”) discloses a PWS for decorative plants including a water source, a water pump, water distribution tubing and a plurality of plant pots. The Snyder system has adjustable timing of the watering, water distribution tubing with multiple branches for multiple plants and valves to prevent flooding. The water distribution tubing of the Snyder system also includes a pressure sensor to sense water pressure in the tubing as a diagnostic measure.
U.S. Pat. No. 4,873,790 (“Laterza”) discloses a plant spinner designed to rotate potted plants so as to evenly expose various portions of the plant to the rays of the sun.
U.S. Pat. No. 4,850,386 (“Birely”) discloses a PWS with a monitor for sensing the moisture content of a surrounding medium, the monitor including two electrodes connected in a detector circuit for detecting the impedance between the electrodes. Because Birely uses an inductive detector, its monitor also includes an oscillator which is disclosed to have an operating frequency of no greater than 20 KHz.
U.S. Pat. No. 4,937,972 (“Freitus”) discloses a planter including a lower compartment for housing an electric pump and battery power source, an intermediate reservoir compartment for storing growth solution, and an upper compartment for holding soil and a plant. The pump selectively waters the plant with growth solution from the intermediate compartment. The upper compartment contains a sensor switch assembly that, depending on the quantity of fluid contained in the upper compartment, water switches on and off the electrical connection between the battery power source and the pump. In other words, this sensor/switch assembly causes the pump to switch on and off and thereby controls the selective watering of the plant. The sensor/switch assembly is located inside the upper compartment and can include resistive, capacitive, optical or other detectors for sensing the level of fluid the upper compartment. Alternatively, the Freitus system may utilize conventional electronic moisture sensors for measuring the amount of moisture present in the soil contained in the upper compartment.
U.S. Pat. No. 5,097,626 (“Mordoch”) discloses a PWS with a variable vacuum moisture sensor, located in the soil in the vicinity of a plant's root. Based on operation of the moisture sensor, the Mordoch PWS opens and closes a watering tube with variations in pressure created by the variable vacuum.
U.S. Pat. No. 5,749,170 (“Furuta”) discloses a couple of embodiments of a PWS with a planter, specifically a pot-shaped case having a space shaped and sized to hold a flowerpot therein. One embodiment of Furuta PWS (see Furuta at FIGS. 1-3 and associated discussion) further includes a moisture sensor that is placed in the soil of the flowerpot. The automatic plant watering operation of Furuta is controlled by a controller using input from the soil moisture sensor and also input from a timer. Another embodiment of Furuta (see Furuta at FIGS. 5-14 and associated discussion) includes three water level sensors S1, S2, S3. Sensors S1 and S2 are disclosed to be located in the interior space of a water tank located around the peripheral wall of the flowerpot, and to sense the level of water in the water tank. Furuta does not disclose any details about how its soil moisture sensors or water tank level sensors operate, such as whether they are electrical or optical.
U.S. Pat. No. 5,956,899 (“DiOrio”) discloses a PWS with a planter and a reservoir. The DiOrio PWS includes a porous ceramic moisture sensor. The DiOrio moisture sensor located at the distal end of a vent tube so that it can be placed at various levels in the soil of the planter so as to vary the level of wetness or dryness for a particular plant.
U.S. Pat. No. 7,222,454 (“Chen”) discloses a PWS including plant pots, a reservoir, a submersible pump, discharge hoses and soaker hoses. Chen also includes a sensor for detecting a low water level in the reservoir. Chen does not disclose any details about how its reservoir level sensor operates.
U.S. published application 2003/0140557 (“Lyon”) discloses a self-regulating watering system including a modular reservoir. The amount of watering is regulated by an air seal that seals upon a moist condition such that air can no longer enter the reservoir. This creates a vacuum, of sorts, and stops the flow of water out of the reservoir until the air seal becomes dry and again opens.
U.S. published application 2004/0059509 (“Anderson”) discloses a soil moisture sensor. In its Background section, Anderson states the following in regard to certain types of soil moisture sensors: “A variety of sensors have been developed to detect moisture in various media. These include conductivity sensors, bulk dielectric constant sensors, time domain reflectometer or transmissometer (TDR or TDT) type sensors, and various oscillator devices, the majority of which exploit the high dielectric constant of water to extrapolate moisture content in the medium. In particular, TDR type sensors have been used over the past several years to measure the water content in various applications. Such applications include detecting volumetric soil moisture, determining liquid levels in tanks, and determining moisture content in paper mills and granaries. A major setback in determining volumetric moisture content in a medium is the influence of conductive materials in the medium of interest. For example, soil conductivity is a function of the ion content of the soil and of its temperature. Salts from irrigation water and/or fertilizer can build up in the soil and cause significant errors in TDR-based moisture readings. Because of the uncertainty in moisture readings caused by conductivity, many of the TDR sensors now available are ‘relative’ sensors. This means that the sensor does not report absolute moisture content readings, but uses reference points obtained through testing. In essence, the moisture sensor does not report absolute moisture content readings, but reports a ‘wetter than’ or ‘drier than’ condition based on the relative difference of the conductivity-dependent moisture content reading and the reference reading. Unfortunately, the readings from these ‘relative’ sensors do not remain in synchronism with the true or ‘absolute water content of the medium, but fluctuate with time. For example, the salinity (ionic content) of soil may fluctuate with season. In such a case, the original reference point becomes an inaccurate indicator of the moisture level of the medium.”
With respect to this discussion of “relative” soil moisture sensors in Anderson, it is noted that the sensors there under discussion there are TDT and TDR type sensors and are not simple, resistive soil moisture sensors. The TDR (or Time Domain Reflectometer) is a resistive type sensor whose operation and discussed at the published Wikipedia website http://en.wikipedia.org/wiki/Time-domain_reflectometer as of 23 Oct. 2007: “A time-domain reflectometer (TDR) is an electronic instrument. A TDR transmits a fast rise time pulse along [a] conductor. If the conductor is of a uniform impedance and properly terminated, the entire transmitted pulse will be absorbed in the far-end termination and no signal will be reflected back to the TDR. But where impedance discontinuities exist, each discontinuity will create an echo that is reflected back to the reflectometer (hence the name). Increases in the impedance create an echo that reinforces the original pulse while decreases in the impedance create an echo that opposes the original pulse. The resulting reflected pulse that is measured at the output/input to the TDR is displayed or plotted as a function of time and, because the speed of signal propagation is relatively constant for a given transmission medium, can be read as a function of cable length. This is similar in principle to radar. TDR is used to determine soil moisture water content in porous media, where over the last two decades substantial advances have been made; including in soils, grains and food stuffs, and in sediments. The key to TDR's success is its ability to accurately determine the permittivity (dielectric constant) of a material from wave propagation, and the fact that there is a strong relationship between the permittivity of a material and its water content, as demonstrated in the pioneering works of Hoekstra and Delaney (1974) and Topp et al. (1980). The TDR method is a transmission line technique, and determines an apparent TDR permittivity (Ka) from the travel time of an electromagnetic wave that propagates along a transmission line, usually two or more parallel metal rods embedded in a soil or sediment. TDR probes are usually between 10 and 30 cm in length and connected to the TDR via a coaxial cable.”
To put it more simply, TDR uses the affect that a resistance of the soil will have on the time it takes to transmit a propagating wave in a conductor. This requires complex equipment to generate the appropriate pulses, to measure received reflections, to measure times and to analyze and interpret the results.
U.S. published application 2005/0199842 (“Parsons”) discloses an irrigation system including a soil moisture sensor. The Parsons system is designed to water large areas such as parks, golf courses or agricultural fields. The soil moisture sensor uses a chamber formed by membranes which is buried in the soil and detects moisture through detection of pressure and hygroscopic force.
U.S. published application 2005/0240313 (“Cartwright”) discloses a PWS including a digital moisture monitor. The digital moisture monitor includes two alternating current (AC) conduction type moisture sensors. Each AC sensor includes two probe tips which will transfer energy therebetween at a rate determined by the moisture content of the soil.
U.S. published application 2006/0290360 (“Lee”) discloses a capacitive soil moisture sensor for use in an irrigation system. Two electrodes are inserted into the soil to form a capacitor with the soil therebetween acting as the dielectric. A change in soil moisture causes the capacitance of the capacitor to change.
U.S. published application 2007/0145984 (“McDermid”) discloses a soil moisture sensor system configured to receive soil between parallel plates. A processor determines soil moisture content based on capacitive measurement taken between the parallel plates.
There are many kinds of “absolute” soil moisture sensors that operate by directly measuring the amount of moisture in the soil, rather than using a measure relative to a calibrated value or values set by the users. Some absolute soil moisture sensors are disclosed in the following articles: (i) “Aqua Pro Sensors A Complete Moisture Sensing And Control System” published at http://www.aquapro-sensors.com as of 10 Oct. 2007; (ii) “Theory Of ECH20 Probes' Operation” published at http://www.decagon.com/Ech20/theory as of 10 Oct. 2007; (iii) “Monitoring Temporal Soil Moisture Variability With Depth Using Calibrated In-Situ Sensors” by Hymer et al. published at http://www.tucson.ars.ag.gov/salsa! archive/publications/ams-preprints/hymer.html (discloses a resistive type of sensor that uses TDR technology); (iv) “Using Soil Moisture Sensors for Making Irrigation Management Decisions in Virginia” by Thomson et al. published at http://www.ext.vt.edu/pubs/rowcrop/442-024/442-024.html#L2.plates.
Description Of the Related Art Section Disclaimer: To the extent that specific publications are discussed above in this Description of the Related Art Section, these discussions should not be taken as an admission that the discussed publications (for example, published patents) are prior art for patent law purposes. For example, some or all of the discussed publications may not be sufficiently early in time, may not reflect subject matter developed early enough in time and/or may not be sufficiently enabling so as to amount to prior art for patent law purposes. To the extent that specific publications are discussed above in this Description of the Related Art Section, they are all hereby incorporated by reference into this document in their respective entirety(ies).